Synonyms for Chilling (same or very similar meaning)
WordNet sense 1 (the process of becoming cooler; a falling temperature):
cooling, temperature reductionWordNet sense 2 (so scary as to cause chills and shudders):
scary, shivery, scarey, shudderyWordNet sense 3 (causing alarm or fear):
alarmingFrom the ODE community, based on WordNetadd/edit